Semi-automatic firearms, such as rifles and shotguns, are designed to fire a round of ammunition, such as a cartridge or shot shell, in response to each squeeze of the trigger of the firearm, and thereafter automatically load the next shell or cartridge from the firearm magazine into the chamber of the firearm. During firing, the primer of the round of ammunition ignites the propellant inside the round, producing an expanding column of high pressure gases within the chamber and barrel of the firearm. The force of this expanding gas propels the bullet/shot of the cartridge or shell down the barrel.
In some types of semi-automatic rifles and shotguns, a portion of the expanding gases will be directed through a duct or port that interconnects the barrel of the firearm to a gas operating system, such as a piston assembly that houses an axially moveable gas piston, or a gas impingement system that directs the expanding gases to impinge on a bolt assembly within a receiver of the firearm. The barrel and the gas operating system typically are coupled to the receiver and aligned with the bolt assembly of the firearm so that the gas operating system can act on the bolt assembly as part of the semi-automatic loading and operation of the firearm so as to cause the rearward motion of the bolt assembly. This rearward motion of the bolt assembly opens the chamber, ejects the empty shell or cartridge casing, and thereafter loads another shell or cartridge into the chamber, after which the bolt returns to a locked position for firing as the expanding gases dissipate or are bled off. The barrel further must be connected in alignment with the gas system to facilitate proper operation of the gas system.
In addition, in such semi-automatic and automatic firearms, it is desirable that the barrel be easily replaceable to enable change of calibers of ammunition to be used in the firearm and/or to provide for replacement of damaged barrels or use of barrels of different lengths for different end use scenarios. The changeout of barrels is, however, complicated by the use of various hand guards and accessory rail assemblies typically mounted about the barrels of such firearms, as well as the increasing use of monolithic or one-piece receiver and hand guard assemblies. Typically, such hand guards must be removed from the firearm prior to the removal and replacement of the barrel, increasing the difficulty and time required for barrel change-out.
Accordingly, it can be seen that a need exists for a barrel mounting and retention assembly that addresses the foregoing and other related and unrelated problems in the art.